diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index 2c70d82..c34a4d7 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -2658,10 +2658,10 @@ function system_preprocess_block(&$variables) {
   list($plugin_id) = explode(':', $variables['plugin_id'] . ':');
   switch ($plugin_id) {
     case 'system_powered_by_block':
-      $variables['attributes_array']['role'] = 'complementary';
+      $variables['attributes']['role'] = 'complementary';
       break;
     case 'system_help_block':
-      $variables['attributes_array']['role'] = 'complementary';
+      $variables['attributes']['role'] = 'complementary';
       break;
     case 'system_menu_block':
       $variables['attributes']['role'] = 'navigation';